CN113278188A

CN113278188A - High-toughness strain-responsive graphene oxide conductive hydrogel and preparation method and application thereof

Info

Publication number: CN113278188A
Application number: CN202110426144.3A
Authority: CN
Inventors: 厉世能; 何潇枫; 孙迦勒; 吴强; 李倩
Original assignee: Zhejiang A&F University ZAFU
Current assignee: Zhejiang A&F University ZAFU
Priority date: 2021-04-20
Filing date: 2021-04-20
Publication date: 2021-08-20
Anticipated expiration: 2041-04-20
Also published as: CN113278188B

Abstract

The invention discloses a high-toughness strain response graphene oxide conductive hydrogel as well as a preparation method and application thereof, and belongs to the field of high polymer materials. Hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is used as a cross-linking agent, and is uniformly mixed with a monomer, an initiator, chitosan and chitosan modified graphene oxide (CS @ GO) and subjected to thermal initiation polymerization reaction to obtain nano composite hydrogel; and then, placing the obtained nano composite hydrogel in a sodium chloride solution for soaking treatment, utilizing sodium chloride to induce chitosan molecules to form a chain entanglement structure to enhance a polymer network structure, and simultaneously endowing sodium ions with the conductive property of the chitosan molecules so as to finally prepare the high-toughness conductive hydrogel. The conductive hydrogel prepared by the method has excellent mechanical properties and excellent strain-conductive response characteristics, and is suitable for popularization and application in the market.

Description

High-toughness strain-responsive graphene oxide conductive hydrogel and preparation method and application thereof

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to a preparation method of a high-toughness strain response graphene oxide conductive hydrogel.

Background

As a novel 'soft and wet' material, the hydrogel has excellent and controllable physicochemical properties, so that the hydrogel can be widely applied to various fields such as tissue engineering, biomedical treatment, bionic sensing and the like. The conductive hydrogel has the double characteristics of 'softness and wetness' and 'conductivity', and is expected to be applied to the advanced fields of electronic skins, intelligent sensors, super capacitors and the like. However, the poor mechanical properties severely limit the long-term usability and safety of the practical applications. Xu and the like take reduced graphene oxide as conductive filler, and hydrogel obtained by compounding the reduced graphene oxide with a polyvinyl alcohol/borax system has excellent strain sensitivity. Yan et al use dopamine to reduce graphene oxide as a conductive filler in combination with regenerated cellulose nanosheets to obtain the conductive nanocomposite hydrogel through self-assembly. However, the hydrogel is complicated in preparation process and undesirable in mechanical properties, and has maximum values of tensile strength and elongation at break of 130kPa and 50%, respectively.

Patent specification with publication number CN 110183688A discloses a preparation method of composite conductive hydrogel, which mixes acrylamide, ammonium persulfate, N-methylene bisacrylamide and tetramethylethylenediamine, and introduces self-made flax fiber as conductive filler to prepare composite hydrogel with excellent conductive performance. However, the system is complicated to prepare and has low tensile strength and elongation at break. At present, the mismatching between the poor mechanical properties of the conductive hydrogel and the high mechanical properties required in practical application hinders the further development and the application field expansion thereof.

To address this problem, researchers have utilized different reinforcement strategies to impart high mechanical properties to conductive hydrogels. Wang et al introduced sodium proteinate and reduced graphene oxide into polyacrylamide hydrogel to prepare conductive hydrogel. The hydrogel elongation at break was as high as about 2400%, but the tensile strength was only 160 kPa. Patent specification CN 112142918A discloses a preparation method of cellulose-based conductive hydrogel: adding cellulose into zinc chloride solution, taking acrylonitrile and acrylamide as monomers, and grafting the monomers on the cellulose. The resulting hydrogel had good elongation at break, but poor mechanical strength. Fu et al have synthesized the high-strength conductive composite hydrogel by constructing a polyaniline/polyacrylamide-co-hydroxyethyl methacrylate interpenetrating network structure. The tensile strength of the hydrogel is as high as 7.27MPa, but the breaking elongation is only 220%.

Patent specification with publication number CN 111040197 a discloses a high-strength multifunctional ion-conductive hydrogel, and a preparation method and application thereof, in which solid gel prepared from polyvinyl alcohol and a beta-cyclodextrin aqueous solution is soaked in a polyacrylic acid/water-soluble salt mixed solution to obtain the ion-conductive hydrogel. The tensile strength of the hydrogel can reach 1.73MPa, but the breaking elongation is only 627%.

In summary, the mechanical properties of the current conductive hydrogel are improved to a certain extent, but the phenomenon of imbalance among mechanical parameters (strength and toughness) still exists, which greatly limits further application and development of the conductive hydrogel.

Therefore, how to develop a conductive hydrogel material with both strength and toughness is one of the research hotspots and difficulties to be solved in the art.

Disclosure of Invention

In view of the above, the present invention provides a preparation method of a graphene oxide conductive hydrogel with high toughness and strain response, aiming at the problems existing in the prior art.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of high-toughness strain-responsive graphene oxide conductive hydrogel comprises the following specific steps:

1) adding 1-6 parts by weight of chitosan, 0.01-4 parts by weight of chitosan modified graphene oxide and 10-30 parts by weight of acrylamide monomer into a container at room temperature, and then adding 50-250 parts by weight of solvent to mix to form a uniform solution;

2) adding 5-20 parts of hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups and 0.01-0.06 part of initiator into the solution obtained in the step 1) at normal temperature, uniformly stirring, and then reacting at 30-60 ℃ for 2-36 hours to obtain hyperbranched polysiloxane crosslinked composite hydrogel;

3) and (3) soaking the composite hydrogel obtained in the step 2) in a sodium chloride solution for 1-24 hours to finally prepare the high-strength and high-toughness strain response graphene oxide conductive hydrogel.

Preferably, the acrylamide monomer is acrylamide, N-isopropylacrylamide, N-methylolacrylamide, N-dimethylacrylamide or methacrylamide. The monomer adopted by the invention has high reaction activity, and is cheap and easy to obtain.

More preferably, the solvent is acetic acid or hydrochloric acid aqueous solution, and the concentration is 0.2-3.0 vol%. Wherein, the purpose of introducing the dilute acid is to ensure the effective swelling of the chitosan molecular chain and obtain a uniform reaction system.

Preferably, the preparation method of the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups simultaneously comprises the following steps: uniformly mixing 10 parts of trialkoxysilane containing epoxy groups, 5-10 parts of trialkoxysilane containing vinyl groups, 5-10 parts of trialkoxysilane containing alkyl groups and 15-25 parts of distilled water according to a molar ratio, adding 20-70 parts of solvent absolute ethyl alcohol, and slowly dripping a catalyst under the condition of stirring; after the dropwise adding is finished, heating to 35-70 ℃, reacting for 2-10 hours, and then carrying out vacuum drying to obtain hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups; wherein the catalyst is acetic acid, hydrochloric acid, sulfuric acid or p-toluenesulfonic acid.

In the preparation method, the hyperbranched polysiloxane with multiple functional groups can be synthesized by utilizing acid-catalyzed hydrolysis condensation reaction, and the method is simple and easy to implement and has no impurities; and the graphene oxide can form multiple functions (covalent bonds, chemical bonds and hydrogen bonds) with a polymer chain, a chitosan molecular chain and chitosan modified graphene oxide simultaneously by using the graphene oxide as a cross-linking agent so as to play a role in strengthening and toughening.

Further, the trialkoxysilane containing epoxy groups is at least one of 3-glycidoxypropyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane; the trialkoxysilane containing vinyl is at least one of gamma-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, gamma-methacryloxypropyltriethoxysilane and vinyltris (beta-methoxyethoxy) silane; the alkyl-containing trialkoxysilane is at least one of methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane and N-propyltriethoxysilane.

Preferably, the preparation method of the chitosan modified graphene oxide comprises the following steps: adding 0.5-2g of chitosan into 0.5-1.5mg/ml of graphene oxide solution at room temperature, adding 1.5-3ml (2 vol%) of acetic acid under uniform stirring, continuously stirring for 2-4h, and standing; then adding 0.3-2.5g of chitosan again, continuously stirring and carrying out ultrasonic treatment for 1-6h to finally prepare chitosan modified graphene oxide; the graphene oxide is prepared according to an improved Hummers method.

In the preparation method, the surface modification treatment is carried out on the graphene oxide by utilizing the chitosan, so that the dispersion of the graphene oxide in the dilute acid aqueous solution is promoted, a uniform reaction system is obtained, and the nano-reinforcing effect is fully exerted.

Preferably, the initiator is at least one of potassium persulfate, ammonium persulfate and sodium persulfate; the chitosan has a molecular weight of 15000-400000 and a deacetylation degree of 80-98%; the concentration of the sodium chloride solution is 30-360 g/L.

In the preparation method, on one hand, the introduction of sodium chloride can promote chitosan chains to form a highly entangled structure, which is beneficial to enhancing the mutual correlation among polymer chains and between the polymer chains and graphene oxide and improving the mechanical property of a polymer network; on the other hand, the existence of sodium ions also endows the hydrogel with excellent conductivity so as to finally prepare the high-toughness conductive hydrogel.

The graphene oxide conductive hydrogel prepared by the method disclosed by the invention is excellent and balanced in mechanical property (tensile strength: 1.50MPa, and fracture energy: 15.26 MJ.m)^-3) And the conductive material also has wide strain conductive response performance (response deformation range is 0-1200 percent), and is suitable for market popularization and application.

The high-toughness strain-responsive graphene oxide conductive hydrogel prepared by the method has potential application in the field of wearable electronic equipment, such as monitoring of human limb movement.

According to the technical scheme, compared with the prior art, the high-toughness strain response graphene oxide conductive hydrogel and the preparation method and application thereof provided by the invention have the following excellent effects:

the preparation method comprises the steps of uniformly mixing hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups as a cross-linking agent with a monomer, an initiator, chitosan and chitosan modified graphene oxide (CS @ GO) and carrying out thermal initiation free radical polymerization reaction to obtain the nano composite hydrogel; and then, the obtained nano composite hydrogel is placed in a sodium chloride solution for soaking treatment, and the sodium chloride is utilized to induce chitosan molecules to form a chain entanglement structure so as to reinforce the polymer network structure. Meanwhile, the existence of sodium ions can also endow the hydrogel with conductive characteristics, so that the high-toughness conductive hydrogel is finally prepared. The conductive hydrogel prepared by the method has excellent mechanical properties and excellent strain-conductive response characteristics, and is suitable for popularization and application in the market.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a stress-strain curve of the synthetic hydrogels of comparative example one, comparative example two, comparative example three, and example five.

Fig. 2 is a photograph of the example five synthesized high-toughness strain-responsive graphene oxide conductive hydrogel in tension, compression, bending and knotting.

FIG. 3 is a schematic diagram of an application of the high-toughness strain-responsive graphene oxide conductive hydrogel synthesized in the fifth embodiment in monitoring finger deformation.

Fig. 4 is a photograph demonstrating brightness change of a small bulb under cyclic compression deformation of the high-toughness strain-responsive graphene oxide conductive hydrogel synthesized in the fifth embodiment.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention discloses a preparation method of high-toughness strain-responsive graphene oxide conductive hydrogel.

The present invention will be further specifically illustrated by the following examples for better understanding, but the present invention is not to be construed as being limited thereto, and certain insubstantial modifications and adaptations of the invention by those skilled in the art based on the foregoing disclosure are intended to be included within the scope of the invention.

Example one

1) Preparation of hyperbranched polysiloxane containing epoxy group, vinyl group and alkyl group

Uniformly mixing 1mol of 3-glycidoxypropyltrimethoxysilane, 1mol of gamma-methacryloxypropyltrimethoxysilane and 0.5mol of methyltrimethoxysilane with 1.5mol of distilled water according to the mol ratio, adding 4.5mol of absolute ethyl alcohol, and slowly dripping hydrochloric acid under the stirring condition; after the dropwise addition, the temperature is raised to 35 ℃, and the reaction is carried out for 2 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 0.5g chitosan was dispersed in the added GO solution (0.5mg/ml), 2ml (2 vol%) acetic acid was added under uniform stirring, left to stand after 2h of continuous stirring, then 0.3g chitosan was added again and stirring was continued and sonication was continued for 3 h.

3) 0.3g of chitosan having a molecular weight of 15000 and a degree of deacetylation of 80%, 6g N-isopropylacrylamide and 0.003g of CS @ GO prepared in step 2) were added to a vessel by weight at room temperature, 38ml (0.2 vol%) of aqueous hydrochloric acid was added and mixed to form a homogeneous solution.

4) Adding 0.26ml of the hyperbranched polysiloxane prepared in the step 1) and 3.6mg of ammonium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 10 hours at 30 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) in 62g/L of sodium chloride solution for 3 hours to obtain the high-toughness strain-responsive graphene oxide conductive hydrogel.

Example two

1) Preparing hyperbranched polysiloxane simultaneously containing epoxy groups, vinyl groups and alkyl groups.

Uniformly mixing 1mol of 3-glycidoxypropyltrimethoxysilane, 0.5mol of gamma-methacryloxypropyltrimethoxysilane and 1mol of methyltrimethoxysilane with 2.5mol of distilled water according to the mol ratio, adding 3.5mol of absolute ethyl alcohol, and slowly dripping acetic acid under the stirring condition; after the dropwise addition, the temperature is raised to 40 ℃, and the reaction is carried out for 6 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 2g of chitosan was added to the GO solution (1.5mg/ml), 3ml (2 vol%) of acetic acid was added with uniform stirring, stirring was continued for 4h and then left to stand. Then 1.3g of chitosan was added again and stirring and sonication was continued for 1 h.

3) 0.8g of chitosan with a molecular weight of 280000 and a degree of deacetylation of 89%, 3g of N-isopropylacrylamide and 0.2g of CS @ GO prepared in step 2) were added to a vessel by weight at room temperature, and 46ml (1.2 vol%) of aqueous hydrochloric acid was added and mixed to form a homogeneous solution.

4) Adding 0.4ml of the hyperbranched polysiloxane prepared in the step 1) and 4.2mg of potassium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 8 hours at 52 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) in 48g/L sodium chloride solution for 8 hours to obtain the high-toughness strain response graphene oxide conductive hydrogel.

EXAMPLE III

Uniformly mixing 1mol of 3-glycidoxypropyltrimethoxysilane, 0.8mol of gamma-methacryloxypropyltrimethoxysilane and 1mol of ethyltrimethoxysilane with 2.1mol of distilled water according to the mol ratio, adding 3.5mol of absolute ethyl alcohol, and slowly dripping p-toluenesulfonic acid under the stirring condition; after the dropwise addition, the temperature is raised to 44 ℃, and the reaction is carried out for 6 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 1.5g chitosan was added to the GO solution (1mg/ml), 3ml (2 vol%) acetic acid was added with uniform stirring, stirring was continued for 3h and then left to stand. Then 2.5g chitosan was added again and stirring and sonication continued for 6 h.

3) 1.3g of chitosan having a molecular weight of 400000 and a degree of deacetylation of 82%, 3g of N-methylolacrylamide and 0.2g of CS @ GO prepared in step 2) were added by weight to a vessel at room temperature, 46ml (2.5 vol%) of an aqueous acetic acid solution was added and mixed to form a homogeneous solution.

4) Adding 0.32ml of the hyperbranched polysiloxane prepared in the step 1) and 6.1mg of potassium persulfate into the solution obtained in the step 3) under the condition of normal temperature, and stirring to form a uniform solution. And reacting for 6 hours at 47 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) placing the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) into a 120g/L sodium chloride solution to be soaked for 12 hours, so as to obtain the high-toughness strain response graphene oxide conductive hydrogel.

Example four

Uniformly mixing 1mol of 2- (3, 4-epoxy cyclohexyl) ethyl trimethoxy silane, 0.6mol of vinyl trimethoxy silane, 0.5mol of propyl trimethoxy silane and 2.3mol of distilled water according to the mol ratio, adding 5.0mol of absolute ethyl alcohol, and slowly dripping sulfuric acid under the stirring condition; after the dropwise addition, the temperature is raised to 31 ℃, and the reaction is carried out for 8 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 1.2g chitosan was added to the GO solution (0.7mg/ml), 2.1ml (2 vol%) acetic acid was added with uniform stirring, stirring was continued for 2.5h and then left to stand. Then 0.8g chitosan was added again and stirring and sonication was continued for 5 h.

3) 0.5g of chitosan having a molecular weight of 60000 and a degree of deacetylation of 87%, 7g N-methylolacrylamide and 0.8g of CS @ GO prepared in step 2) were added to a vessel by weight at room temperature, 60ml (3 vol%) of an aqueous acetic acid solution was added and mixed to form a homogeneous solution.

4) Adding 0.38ml of the hyperbranched polysiloxane prepared in the step 1) and 13mg of potassium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 4 hours at 60 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) in 70g/L sodium chloride solution for 24 hours to obtain the high-toughness strain response graphene oxide conductive hydrogel.

EXAMPLE five

Uniformly mixing 1mol of 2- (3, 4-epoxy cyclohexyl) ethyl triethoxysilane, 0.4mol of vinyl triethoxysilane, 0.8mol of methyl triethoxysilane and 1.8mol of distilled water according to a mol ratio, adding 8.0mol of anhydrous ethanol, and slowly dripping acetic acid under the condition of stirring; after the dropwise addition, the temperature is raised to 70 ℃, and the reaction is carried out for 6 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 0.9g of chitosan was added to the GO solution (1.1mg/ml), 1.7ml (2 vol%) of acetic acid was added with uniform stirring, stirring was continued for 3.5h and then left to stand. Then 2.2g chitosan was added again and stirring was continued and sonication was continued for 3 h.

3) 1.2g of chitosan having a molecular weight of 250000 and a degree of deacetylation of 92%, 8.8g of methacrylamide and 0.035g of CS @ GO prepared in step 2) were added by weight to a vessel at room temperature, 50ml (2.8 vol%) of an aqueous acetic acid solution was added and mixed to form a homogeneous solution.

4) Adding 0.24ml of the hyperbranched polysiloxane prepared in the step 1) and 18mg of potassium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 15 hours at the temperature of 45 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) in 180g/L sodium chloride solution for 2 hours to obtain the high-toughness strain-responsive graphene oxide conductive hydrogel.

EXAMPLE six

Uniformly mixing 0.5mol of 2- (3, 4-epoxycyclohexyl) ethyl triethoxysilane, 0.5mol of 3-glycidoxypropyltrimethoxysilane, 0.3mol of vinyl triethoxysilane, 0.8mol of ethyl triethoxysilane and 1.5mol of distilled water according to a mol ratio, adding 10mol of anhydrous ethanol, and slowly dropwise adding p-toluenesulfonic acid under the stirring condition; after the dropwise addition, the temperature is raised to 53 ℃, and the reaction is carried out for 3 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 1.9g of chitosan was added to the GO solution (1.4mg/ml), 2.7ml (2 vol%) of acetic acid was added with uniform stirring, stirring was continued for 3h and then left to stand. Then 2.4g chitosan was added again and stirring was continued and sonication was continued for 4.5 h.

3) 0.7g of 85000 molecular weight chitosan with a degree of deacetylation of 81%, 6g N, N-dimethylacryloyl and 1.2g of CS @ GO prepared in step 2) were added to a vessel by weight at room temperature, 15ml (0.8 vol%) of aqueous acetic acid was added and mixed to form a homogeneous solution.

4) Adding 0.22ml of the hyperbranched polysiloxane prepared in the step 1) and 15mg of sodium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 36 hours at 30 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) in 300g/L sodium chloride solution for 12 hours to obtain the high-toughness strain response graphene oxide conductive hydrogel.

EXAMPLE seven

Uniformly mixing 0.4mol of 2- (3, 4-epoxycyclohexyl) ethyl triethoxysilane, 0.6mol of 3-glycidoxypropyltrimethoxysilane, 1.0mol of vinyl triethoxysilane, 0.5mol of ethyl triethoxysilane, 0.3mol of ethyl trimethoxysilane and 1.7mol of distilled water according to a mol ratio, adding 10mol of absolute ethanol, and slowly dropwise adding p-toluenesulfonic acid under the stirring condition; after the dropwise addition, the temperature is raised to 50 ℃, and the reaction is carried out for 3 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 1.3g of chitosan was added to the GO solution (1.3mg/ml), 1.6ml (2 vol%) of acetic acid was added with uniform stirring, stirring was continued for 2h and then left to stand. Then 0.4g chitosan was added again and stirring was continued and sonication was continued for 1.5 h.

3) 0.92g of chitosan with a molecular weight of 120000 and a degree of deacetylation of 83%, 6.5g of acrylamide and 0.05g of CS @ GO prepared in step 2) were added to a vessel by weight at room temperature, 28ml (1.4 vol%) of aqueous acetic acid was added and mixed to form a homogeneous solution.

4) Adding 0.4ml of the hyperbranched polysiloxane prepared in the step 1) and 6.7mg of sodium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 28 hours at 56 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) placing the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) into 320g/L sodium chloride solution to be soaked for 11 hours, so as to obtain the high-toughness strain response graphene oxide conductive hydrogel.

Example eight

Uniformly mixing 0.7mol of 3-glycidoxypropyltrimethoxysilane, 0.3mol of 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane, 0.4mol of gamma-methacryloxypropyltrimethoxysilane, 0.5mol of vinyltriethoxysilane, 0.8mol of methyltrimethoxysilane and 0.1mol of methyltriethoxysilane with 2.3mol of distilled water according to a mol ratio, adding 14mol of absolute ethyl alcohol, and slowly dropwise adding hydrochloric acid under the stirring condition; after the dropwise addition, the temperature is raised to 40 ℃, and the reaction is carried out for 6 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 2g of chitosan was added to the GO solution (0.5mg/ml), 2.6ml (2 vol%) of acetic acid was added with uniform stirring, stirring was continued for 4h and then left to stand. Then 0.5g chitosan was added again and stirring and sonication was continued for 2 h.

3) 1.3g of chitosan having a molecular weight of 120000 and a degree of deacetylation of 87%, 7.8g of acrylamide and 0.07g of CS @ GO prepared in step 2) were charged by weight into a vessel at room temperature, 42ml (2.4 vol%) of an aqueous acetic acid solution was added, and mixed to form a homogeneous solution.

4) Adding 0.23ml of the hyperbranched polysiloxane prepared in the step 1) and 13mg of ammonium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 25 hours at 44 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) placing the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) into 360g/L sodium chloride solution to be soaked for 17 hours, so as to obtain the high-toughness strain response graphene oxide conductive hydrogel.

Example nine

Uniformly mixing 0.9mol of 3-glycidoxypropyltrimethoxysilane, 0.1mol of 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane, 0.6mol of gamma-methacryloxypropyltrimethoxysilane, 0.3mol of vinyltriethoxysilane, 0.8mol of N-propyltriethoxysilane, 0.1mol of propyltrimethoxysilane and 2.5mol of distilled water according to a mol ratio, adding 11mol of absolute ethanol, and slowly dropwise adding sulfuric acid under the stirring condition; after the dropwise addition, the temperature is raised to 52 ℃, and the reaction is carried out for 2.5 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 1.9g of chitosan was added to the GO solution (0.9mg/ml), 2.7ml (2 vol%) of acetic acid was added with uniform stirring, stirring was continued for 4h and then left to stand. Then 2.1g chitosan was added again and stirring and sonication was continued for 6 h.

3) 1.8g of chitosan with a molecular weight of 120000 and a degree of deacetylation of 97%, 8.3g of acrylamide and 0.9g of CS @ GO prepared in step 2) were added to a vessel by weight at room temperature, 70ml (0.5 vol%) of an aqueous acetic acid solution was added and mixed to form a homogeneous solution.

4) Adding 0.33ml of the hyperbranched polysiloxane prepared in the step 1) and 7.5mg of sodium persulfate into the solution obtained in the step 3) under the condition of normal temperature, and stirring to form a uniform solution. And reacting for 20 hours at 37 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) in 75g/L sodium chloride solution for 10 hours to obtain the high-toughness strain response graphene oxide conductive hydrogel.

Example ten

Uniformly mixing 0.2mol of 2- (3, 4-epoxycyclohexyl) ethyl trimethoxy silane, 0.8mol of 2- (3, 4-epoxycyclohexyl) ethyl triethoxy silane, 0.3mol of gamma-methacryloxypropyl trimethoxy silane, 0.5mol of vinyl tri (beta-methoxyethoxy) silane, 0.6mol of N-propyltriethoxy silane, 0.2mol of propyl trimethoxy silane and 1.8mol of distilled water according to a mol ratio, adding 12.4mol of absolute ethyl alcohol, and slowly dropwise adding acetic acid under the stirring condition; after the dropwise addition, the temperature is raised to 37 ℃, and the reaction is carried out for 6.5 hours under the protection of nitrogen; after the reaction is finished, the hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups is obtained through vacuum drying.

2) Preparation CS @ GO

At room temperature, 1.8g of chitosan was added to the GO solution (1.3mg/ml), 2.5ml (2 vol%) of acetic acid was added with uniform stirring, stirring was continued for 2h and then left to stand. Then 0.7g chitosan was added again and stirring and sonication was continued for 5 h.

3) 1.4g of chitosan of molecular weight 180000 and degree of deacetylation 94%, 7.4g of acrylamide and 0.009g of CS @ GO prepared in step 2) were added to a vessel by weight at room temperature, 36ml (1.5 vol%) of aqueous acetic acid was added and mixed to form a homogeneous solution.

4) Adding 0.28ml of the hyperbranched polysiloxane prepared in the step 1) and 8.5mg of sodium persulfate into the solution obtained in the step 3) under the condition of normal temperature, and stirring to form a uniform solution. And reacting for 16 hours at 55 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

5) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 4) in 30g/L sodium chloride solution for 14 hours to obtain the high-toughness strain response graphene oxide conductive hydrogel.

It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. The method disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the description of the method part.

To further illustrate the excellent effects of the high-toughness strain-responsive graphene oxide conductive hydrogel envisioned and protected by the present invention, the inventors have also performed the following comparative experiments:

comparative example 1

2) 1.2g of chitosan having a molecular weight of 250000 and a degree of deacetylation of 92% and 8.8g of methacrylamide were added by weight to a vessel at room temperature, and 50ml (2.8 vol%) of an aqueous acetic acid solution was added and mixed to form a homogeneous solution.

3) Adding 0.24ml of the hyperbranched polysiloxane prepared in the step 1) and 18mg of potassium persulfate into the solution obtained in the step 3) at normal temperature, and stirring to form a uniform solution. And reacting for 15 hours at the temperature of 45 ℃ to obtain the hyperbranched polysiloxane crosslinked composite hydrogel.

Comparative example No. two

2) Preparation CS @ GO

Comparative example No. three

2) 1.2g of chitosan having a molecular weight of 250000 and a degree of deacetylation of 92% and 8.8g of methacrylamide by weight were added to a vessel at room temperature, 50ml of an aqueous acetic acid solution was added, and mixed to form a uniform solution.

4) And (3) soaking the hyperbranched polysiloxane crosslinked composite hydrogel obtained in the step 3) in 180g/L sodium chloride solution for 2 hours to obtain the hyperbranched polysiloxane crosslinked high-toughness composite hydrogel.

Referring to fig. 1, the stress-strain curves of the alloy are shown in comparison with comparative example one, comparative example two and comparative example three. It can be calculated that the hydrogel prepared in the fifth example has excellent and balanced mechanical properties, and the tensile strength, elongation at break and energy at break can reach 1.50MPa, 1421% and 15.26 MJ.m respectively, compared with the comparative example^-3. Meanwhile, the mechanical properties of the hydrogels after the salt soaking treatment (example five and comparative example three) are obviously better than those of the untreated hydrogels (comparative example one and comparative example two), which shows that the network structure induced by the salt is important for improving the mechanical properties of the hydrogels. In addition, the mechanical properties of the hydrogel can be further improved by the presence of graphene oxide (example five and comparative example three).

Fig. 2 is a digital photograph of mechanical deformation of the conductive hydrogel synthesized in the present invention, and as can be seen from fig. 2, the conductive hydrogel can perform large stretching, compressing, bending and knotting behaviors, which indicates that the graphene oxide conductive hydrogel disclosed in the present invention has excellent mechanical deformation capability, and further proves its superior mechanical properties.

Fig. 3 shows the real-time relative change of the resistance corresponding to the stretching cycle of the conductive hydrogel synthesized in the present invention, and it can be seen from fig. 3 that the resistance of the hydrogel rapidly changes with the change of the stretching deformation, and the resistance can be kept stable well when the stretching deformation is fixed.

And the conductive hydrogel has good strain conductive responsiveness and stability, which is shown in fig. 4 that the brightness of the LED lamp changes significantly with compression deformation. In combination with the above data, the conductive hydrogel disclosed by the invention not only has excellent and balanced mechanical properties, but also has superior strain conductivity responsiveness.

In addition, from the digital photograph of the pulled-up weight of the graphene oxide conductive hydrogel synthesized in the present invention, it was found that the hydrogel can withstand a weight of more than 4.5kg without mechanical failure. The hydrogel is further proved to have excellent mechanical properties and potential practical application prospects.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of high-toughness strain-responsive graphene oxide conductive hydrogel is characterized by comprising the following specific steps:

2. The preparation method of the high-toughness strain-responsive graphene oxide conductive hydrogel according to claim 1, wherein the acrylamide monomer is acrylamide, N-isopropylacrylamide, N-methylolacrylamide, N-dimethylacrylamide or methacrylamide.

3. The preparation method of the high-toughness strain-responsive graphene oxide conductive hydrogel according to claim 1 or 2, wherein the solvent is an acetic acid or hydrochloric acid aqueous solution, and the concentration is 0.2-3.0 vol%.

4. The preparation method of the high-toughness strain-responsive graphene oxide conductive hydrogel according to claim 1, wherein the preparation method of the hyperbranched polysiloxane simultaneously containing epoxy groups, vinyl groups and alkyl groups comprises the following steps: uniformly mixing 10 parts of trialkoxysilane containing epoxy groups, 5-10 parts of trialkoxysilane containing vinyl groups, 5-10 parts of trialkoxysilane containing alkyl groups and 15-25 parts of distilled water according to a molar ratio, adding 20-70 parts of solvent absolute ethyl alcohol, and slowly dripping a catalyst under the condition of stirring; after the dropwise adding is finished, heating to 35-70 ℃, reacting for 2-10 hours, and then carrying out vacuum drying to obtain hyperbranched polysiloxane containing epoxy groups, vinyl groups and alkyl groups; wherein the catalyst is acetic acid, hydrochloric acid, sulfuric acid or p-toluenesulfonic acid.

5. The preparation method of the high-toughness strain-responsive graphene oxide conductive hydrogel according to claim 4, wherein the epoxy-containing trialkoxysilane is at least one of 3-glycidoxypropyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane; the trialkoxysilane containing vinyl is at least one of gamma-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, gamma-methacryloxypropyltriethoxysilane and vinyltris (beta-methoxyethoxy) silane; the alkyl-containing trialkoxysilane is at least one of methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane and N-propyltriethoxysilane.

6. The preparation method of the high-toughness strain-responsive graphene oxide conductive hydrogel according to claim 1, wherein the preparation method of the chitosan-modified graphene oxide comprises the following steps: adding 0.5-2g of chitosan into 0.5-1.5mg/ml of graphene oxide solution at room temperature, adding 1.5-3ml of acetic acid under uniform stirring, continuously stirring for 2-4h, and standing; then adding 0.3-2.5g of chitosan again, continuously stirring and carrying out ultrasonic treatment for 1-6h to finally prepare chitosan modified graphene oxide; the graphene oxide is prepared according to an improved Hummers method.

7. The preparation method of the high-strength-toughness strain-responsive graphene oxide conductive hydrogel according to claim 1, wherein the initiator is at least one of potassium persulfate, ammonium persulfate and sodium persulfate; the chitosan has a molecular weight of 15000-400000 and a deacetylation degree of 80-98%; the concentration of the sodium chloride solution is 30-360 g/L.

8. The high-toughness strain-responsive graphene oxide conductive hydrogel prepared by the method of claim 1.

9. Use of the high-toughness strain-responsive graphene oxide conductive hydrogel prepared by the method according to claim 1 or the high-toughness strain-responsive graphene oxide conductive hydrogel according to claim 8 in wearable electronic equipment.